Core drilling tool and core drilling machine

ABSTRACT

A core drilling tool and an associated core drilling machine are disclosed. An advantageous and permanent connection is ensured between the core drilling tool and the core drilling machine by means of a form-fitting element on the core drilling tool and an assigned form-fitting counterelement on a tool-holding fixture of the core drilling machine. Interlatching between the core drilling tool and the tool-holding fixture of the core drilling machine is made possible via latching elements of the tool-holding fixture preferably only when the form-fitting connection between the form-fitting element and the form-fitting counterelement is effected.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority of German Patent Application No.10 2004 062 912.9 on Dec. 22, 2004.

BACKGROUND OF THE INVENTION

The invention relates to a drilling tool, in particular a core drillingtool, and to a drilling machine comprising a suitable tool-holdingfixture for the reception of a drilling tool of this type.

DE 44 22 342 C2 discloses a core drill and a core drilling machinecomprising a tool-holding fixture suitable for the reception of a coredrill of this type. In this case, the core drilling tool has a shank forfastening to an assigned tool-holding fixture of a core drillingmachine, the shank being designed cylindrically and having a pluralityof depressions, into which balls of the assigned tool-holding fixture ofthe core drilling machine can engage. When a core drilling tool ispushed into the tool-holding fixture, balls held movably in thetool-holding fixture enter the depressions of the shank of the coredrilling tool and then allow force transmission between the coredrilling machine and the core drilling tool.

This design has the disadvantage that torque transmission is broughtabout solely via the balls. This may lead to premature wear,particularly since core drilling tools are exposed to high torques.

SUMMARY OF THE INVENTION

It is an object of the invention to disclose a core drilling tool and acore drilling machine having a tool-holding fixture which can engage thecore drilling tool so as to allow for an improved torque transmissionfrom the tool-holding fixture to the core drilling tool.

This and other objects of the invention are achieved, according to theinvention, by means of a core drilling tool, in particular a core drill,comprising a shank for fastening to an assigned tool-holding fixture ofa core drilling machine, the shank having at least one depression forthe reception of at least one latching element of the tool-holdingfixture, the core drill comprising a form-fitting element which isoffset axially with respect to the depression and is designed forform-fitting connection to a form-fitting counterelement provided on thetool-holding fixture.

Furthermore, the object of the invention is achieved by means of a coredrilling machine comprising a drive for driving a tool-holding fixturehaving a pot-shaped extension with a cavity into which a core drillingtool can be inserted with its shank, and having at least one radiallymovable latching element which allows interlatching with an assigneddepression on the shank of a core drilling tool introduced into thetool-holding fixture, there being provided on the inner wall of thecavity a form-fitting counterelement which is offset axially withrespect to the at least one latching element and is designed forform-fitting connection to a form-fitting element of the core drillingtool.

The object of the invention is in this way achieved in full.

To be precise, according to the invention, irrespective of the latchingelements used, a form-fitting element and a form-fitting counterelementon the core drilling tool, on the one hand, and on the core drillingmachine, on the other hand, are now used, in order to ensure a form-fitbetween the core drilling tool and the core drilling machine.

Thus, according to the invention, a secure connection between the coredrilling tool and the core drilling machine is now ensured by means of aform-fit, without the balls used in the prior art being used in thiscase in order to produce a form-fit. Additionally, however, the at leastone latching element on the tool-holding fixture and the at least oneassigned depression on the core drilling tool are provided, in order tomake it possible that core drilling tools according to the invention canalso be chucked on conventional core drilling machines.

In an advantageous development of the invention, the depression on theshank is designed as a circumferential groove.

One or more latching elements can thus be used in order to allowinterlatching between the circumferential groove of the shank and thetool-holding fixture. By the depression being configured as acircumferential groove, this ensures that no torques of any kind aretransmitted via the latching elements.

The form-fitting element of a shank may preferably be designed as apolygon, in particular as a square, a hexagon or an octagon.

Correspondingly, the form-fitting counterelement on the tool-holdingfixture may be designed as a polygon, in particular as a square, ahexagon or an octagon.

According to a further refinement of the invention, the form-fittingelement is provided at that end of the shank which faces away from theouter end, and the at least one depression is arranged so as to beoffset axially in the direction of the outer end of the shank.

Correspondingly, according to a further refinement of the invention, theform-fitting counterelement on the tool-holding fixture is provided atthe outer end of the inner wall of the cavity, the at least one latchingelement being offset axially with respect to the form-fittingcounterelement in the direction of the inner end of the cavity.

By virtue of these measures, it becomes possible respectively for theform-fitting element and the form-fitting counterelement to be offsetwith respect to the at least one depression and with respect to the atleast one latching element in such a way that interlatching with the atleast one latching element is made possible only when the form-fittingelement engages with a form-fit on the form-fitting counterelement ofthe tool-holding fixture.

It can thereby be ensured that, when the core drilling tool is pushedinto the tool-holding fixture, a proper form-fit between the coredrilling tool and the tool-holding fixture is always ensured. For thispurpose, the core drilling tool merely has to be introduced in thesuitable angular position into the tool-holding fixture and latched.

According to a further refinement of the invention, the shank of thecore drilling tool has a cylindrical basic shape and preferably on itsouter surface a plurality of flattenings.

The shank can thereby be designed with the conventional features, sothat it also becomes possible for core drilling tools according to theinvention to be chucked on conventional core drilling machines in whichforce transmission takes place solely via balls which engage betweendepressions on the outer surface of the core drilling tools anddepressions on the inner surface of the tool-holding fixture. The coredrilling tools according to the invention can thus also be used forconnection to tool-holding fixtures of the “Weldon®” type.

According to an advantageous development of the invention, threelatching elements, which are preferably designed as balls, are arrangedradially movably, at uniform angular intervals in relation to oneanother, in radial bores.

In this case, the latching elements may be secured against falling outoutwards by means of a sleeve which surrounds the extension fromoutside.

In a combination according to the invention of a core drilling machinewith a core drilling tool of the type described above, the form-fittingelement of the core drilling tool is arranged so as to be offset axiallywith respect to the at least one depression of the core drilling tool insuch a way that interlatching with the at least one latching element ismade possible only when the form-fitting element engages with a form-fitonto the form-fitting counterelement of the tool-holding fixture.

This ensures a reliable form-fitting fastening of the core drilling toolon the core drilling machine; and

It goes without saying that the abovementioned features of the inventionand those yet to be explained below can be used not only in thecombination specified in each case, but also in other combinations oralone, without departing from the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is Further features and advantages of the invention may begathered from the following description of a preferred exemplaryembodiment, with reference to the drawing in which:

FIG. 1 shows a side view of a core drilling tool according to theinvention;

FIG. 2 shows a section through the core drilling tool along the lineII-II, and

FIG. 3 shows an assembly drawing in longitudinal section, a coredrilling tool according to the invention, as shown in FIGS. 1 and 2,being inserted into an assigned tool-holding fixture of a core drillingmachine.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 and 2, a core drilling tool according to the invention isdesignated as a whole by the numeral 10.

The core drilling tool 10 has a pot-shaped drill bit 12 which at itsouter edge has a plurality of cutting elements 14 so that a core borecan be produced. The drill bit 12 is closed off by means of a radial endface 28 towards the side lying opposite the cutting elements 14. From anadjoining flanged surface 18 of smaller diameter, a basicallycylindrical shank 16 extends in the direction of an outer end 24. Anattachment in the form of a form-fitting element 20, which is designedas an octagon, is provided contiguous to the flanged surface 18. Thisform-fitting element 20 then has adjoining it the shank 16 with itsbasically cylindrical outer surface. Directly contiguously to the outerend 24 of the shank 16 is provided a depression 22 which is designed asa circumferential groove or annular groove. This depression 22 servesfor the reception of latching elements of an assigned tool-holdingfixture of a core drilling machine. The shank 16 is provided on itscircumferential surface with, overall, four flattenings 26 which make itpossible to connect the core drilling tool 10 to a fixture of theWeldon® type which is conventional in the prior art.

The interaction between a core drilling tool 10 and the tool-holdingfixture 32 of an assigned machine tool 30 is explained in more detailbelow with reference to FIG. 3.

A core drilling machine, designated as a whole by the numeral 30, isillustrated in FIG. 3 solely in its outer region. The core drillingmachine 30 has a drive, indicated by the numeral 36, by means of which ashaft portion 34 can be driven in rotation. As illustrated in FIG. 3,the shaft portion 34 may have a conical form of construction and bescrewed with the aid of a thread 52 to an element driven in rotation bythe drive 36. The tool-holding fixture 32 has an annular collar 38 whichprojects outwards from the thread 52 and from which a pot-shapedextension 40 extends outwards. A cylindrical cavity 42 is provided inthe pot-shaped extension 40. At the outer end of the cavity 42, on theinner wall, a form-fitting counterelement 44 in the shape of an octagonis formed, the shape and size of which are coordinated with theform-fitting element 20 on the core drilling tool 10. In the region ofthe bottom of the cavity 42, latching elements 46 in the shape ofspring-loaded balls are provided in radial bores 48 which pass throughthe wall of the extension 40. Three latching elements, overall, arearranged at uniform angular intervals of 120° in relation to oneanother. The radial bores 48 end towards the inside of the cavity 42with a diameter such that the inserted balls cannot fall into the cavity42. The balls are secured outwardly against falling out by means of asleeve 50 pushed onto the outer wall of the extension 40. The sleeve 50is screwed or otherwise connected, for example by means of a press fit,to the extension 40.

The balls are prestressed inwards in the direction of the cavity 42 bymeans of spring elements (not illustrated). The sprung balls may bereplaced by any other sprung elements, such as, for example, by sprungpins; and

The axial spacing between the latching elements 46 and the assigneddepression 22 in the shape of the circumferential groove on the shank 16of the core drilling tool 10 is selected such that an engagement of thelatching elements 46 or of the balls into the depression 22 is madepossible only when the form-fitting element 20 of the core drilling tool10 engages with a form-fit into the form-fitting counterelement 44 atthe outer end of the cavity 42.

1. A core drill comprising: a pot-shaped drill bit having a first endformed by a radial end surface and having a second end carrying aplurality of cutting elements; a shank extending from said radial endsurface and being configured for engaging an assigned tool-holdingfixture of a core drilling machine; at least one depression provided onsaid shank configured for receiving at least one latching elementprovided on said tool-holding fixture when being in an engaged positionin which said shank is received within a cavity of said tool-holdingfixture and said latching element is latched with said depression; and aform-fitting element which is axially offset from said depression towardsaid radial end surface and is configured for engaging a form-fittingcounterelement provided on said tool-holding fixture for effecting aform-fitting connection to said tool-holding fixture when being in saidengaged position.
 2. The core drill of claim 1, wherein the depressionis configured as a circumferential groove.
 3. The core drill of claim 1,wherein the form-fitting element is configured as a polygon.
 4. The coredrill of claim 3, wherein the form-fitting element has a shape selectedfrom the group formed by a square, a hexagon and an octagon.
 5. The coredrill of claim 1, wherein said form-fitting element is located at anouter end of said shank opposite to said radial surface, and whereinsaid at least one depression is located axially offset from saidform-fitting element toward said radial surface.
 6. The core drill ofclaim 5, wherein said at least one depression is located adjoining theradial end surface so as to allow a latching with said latching elementof said tool-holding fixture only when said form-fitting element isengaged with said form-fitting counterelement when being in said engagedposition.
 7. The core drill of claim 1, wherein said shank has asubstantially cylindrical shape.
 8. The core drill of claim 7, furthercomprising a plurality of flattenings provided on an outer surface ofsaid shank.
 9. A core drilling machine comprising: a drive for driving atool-holding fixture having a pot-shaped extension defining a cavityconfigured for receiving a shank of a core drilling tool; at least oneradially movable latching element provided on said pot-shaped extensionand configured for interlatching with an assigned depression provided onsaid shank of said core drilling tool when being in an engaged position,in which said shank of said core drilling tool is received within saidcavity of said tool-holding fixture; a form-fitting counterelementprovided on an inner wall of said cavity, said form-fittingcounterelement being offset axially with respect to said at least onelatching element and being configured for effecting a form-fittingconnection to a form-fitting element provided on said core drilling toolwhen being in said engaged position.
 10. The core drilling machine ofclaim 9, wherein said form-fitting counter-element is shaped as apolygon.
 11. The core drilling machine of claim 9, wherein saidform-fitting counterelement has a shape selected from the group formedby a square, a hexagon and an octagon.
 12. The core drilling machine ofclaim 9, wherein said form-fitting counter-element is provided at anouter end of said cavity, and wherein said at least one latching elementis axially offset from said form-fitting counterelement toward an innerend of said cavity.
 13. The core drilling machine of claim 9, furthercomprising at least one bore extending radially from an inner wall ofsaid cavity within said pot-shaped extension, a ball being arrangedmovably within said at least one bore, thereby defining a latchingelement.
 14. The core drilling machine of claim 9, further comprisingthree bores being arranged at uniform angular intervals in relation toone another and extending radially from an inner wall of said cavitywithin said pot-shaped extension, a ball being arranged movably withineach of said bores, thereby defining a latching element.
 15. The coredrilling machine of claim 13, further comprising a sleeve surroundingsaid pot-shaped extension from the outside for secured said at least onelatching element against falling out outwards.
 16. A core drillingmachine with a core drilling tool, comprising: a drive for driving atool-holding fixture having a pot-shaped extension defining a cavityconfigured for receiving a shank of said core drilling tool; at leastone radially movable latching element provided on said pot-shapedextension and configured for interlatching with an assigned depressionprovided on said shank of said core drilling tool when being in anengaged position, in which said shank of said core drilling tool isreceived within said cavity of said tool-holding fixture; a form-fittingcounterelement provided on an inner wall of said cavity, saidform-fitting counterelement being offset axially with respect to said atleast one latching element and being configured for effecting aform-fitting connection to a form-fitting element provided on said coredrilling tool when being in said engaged position.
 17. The core drillingmachine of claim 16, wherein said form-fitting element of said coredrilling tool is arranged so as to be offset axially with respect tosaid at least one depression of the core drilling tool in such a waythat latching with said at least one latching element made possible onlywhen said form-fitting element engages with a form-fit on saidform-fitting counterelement of said tool-holding fixture.